hi. for example, can i make an assigned lot type: graveyard cause different custom moodlets to sims depending on their traits?
in base game there already is a "creepy graveyard" moodlet for cowards sims. is it possible for me to make positive moodlets for sims with whichever traits i choose?

i have never created a mod before but i want to start

Yes it is possible. Have you done any tutorials for modding Ts3? When I first began modding a creator pointed me out to these tutorials. I would recommend trying to complete these. Just so you know some very basic things about modding the sims 3. If you have any questions let me know. I'll try to be helpful.

Object Modding

Pure Modding

Adding Interactions to existing objects (Sim)

Localized Coding

Making and Loading Custom Moodlets