Nuff said.

You mean modding as in making mods/hacks to tweak a game setting?
I assume you'd start by checking out the tutorials in the modding section: http://www.modthesims.info/forumdisplay.php?f=8

Or here, for all the sections on modding/meshing/creating: https://www.modthesims.info/wiki...S:Sims_2_Create

You start with an idea of what you want to see in the game and then try to find ways to implement it by reading tutorials and looking at how Maxis and other modders did similar things. If you have an idea and willing to share what it is, maybe someone will be able to point you in the right direction.

I'm going to assume you mean bhav modding. Go here.
http://www.eternal-echo.net/sims/tu...s/interactions/

Then here.
http://www.eternal-echo.net/sims/tu...ions2/index.php

And here.
http://www.sims2workshop.com/index....d&threadID=1195

Then the best thing that I've found to is to go through the really old threads where people asked for help, download the object that they made as a result of that help and open the object in SimPE while reading through the thread to understand why the modder did what they did. The create boards are slow, these days, so don't be discouraged if you ask for help and it takes a long time to get a reply.

I have an idea... someone might beat me to it, but I would want to have an interaction on a mailbox/callphone that changes a lot behaviour. For example, makes it "haunted" regardless of whenever there are graves presented or "earthquake" which causes appliances/plumbing to break more frequently than usual... ect.

I wouldn't do that sort of hack on either of those two objects. Both the phone and the mailbox are objects heavily used by EAxis and both changed with every single EP and even some of the SPs. Trying to modify the options on either when people have different configurations of EPs/SPs and different game versions (UC as opposed to disk version for a start, not even getting into the collections) is just asking for trouble. If you want to do a mod, I'd use a standalone object or ... just something else, not the phone. You can try modding the phone, sure, but you're just making the task harder on yourself. Personally, I'd restrict modding the phone or mailbox to things that actually make sense using those objects, like adding a phone call option - not least because there are a good number of hacks for the phone already and you're also going to risk running into problems conflicting with existing hacks.

What about the trashcan? the black one which I'm referring to.

Do you have any programming experience? If not, then I would not recommend starting with that. You can have it as your end goal, but you'll need to do a lot of tutorials and create other things before you get to a point where that's feasible.

And I agree with Maxon, stay away from the objects automatically present on lot. They are used too much by EA. Not sure about the trash can, but I would not use that either way because they aren't essential for a lot to work and some people delete them. Is there a reason why you don't want to use a custom object?

I know java basics, though I would appreciate what kind of language TS2 requires for modding. I'm willing to learn its too.

You need SimPE to make mods/hacks for Sims 2.

That is the program you need to learn how to use for well over 99% of modding Sims 2.
There are other programs need to make or modify skins and other thing like that.

Sims 2 uses hex code (hexadecimal) for nearly all modding, so learning how it works is a very good idea.
Wiki article here: https://en.wikipedia.org/wiki/Hexadecimal

You only need to use blocks of 8 digits for Sims programming. GUIDs are a good example of Hex codes.

I've mostly been learning Hex by osmosis, until I finally actually figured it out. I can (with a bit of thinking time) count in Hex up to a certain point where I just give up, so I can by no means do the whole "so-and-so in decimal is so-and-so in Hex" - that I leave to the experts - but for most modding uses, learning how Hex numbers work is a very useful skill (just like you can put together any Decimal number with the use of 0-9 in bulks of 10, you can put together any Hex number with 0-9 and A-F in bulks of 16). There are always calculators on the net if you need that: http://www.binaryhexconverter.com/d...o-hex-converter

SimAntics - see here and here

There's a hex converter in SimPE too. In the BCON section.

My suggestion re. what object to use would be to clone a random deco item and add your functions to the clone. Doing it that way makes conflicts much less likely, and makes the programming a lot more straightforward.