how do I trim/ top it off

Im pretty new to growing, and I was wondering how I trim my plants so they grow bigger/wider and not taller! what part do I trim? When should I trim? please help and thank you! ive got one plant that is about a 12 inches and one about 8 inches!

You should YouTube let training and topping...this is your best bet at being successful at doing this

Cut between the 3rd and 4th true nodes for maximum bushiness. I trim as soon as the 5th node starts to develop, some people wait longer. Theres lots of videos and threads on the subject do some research before you do anything. If your plants are already a foot tall then your probably better off with super cropping or LST to keep it short

You can also trim the roots. like they do in Bonsai.
Keeping your plant in smaller containers - "The bigger the container, the bigger that plant"
There are certain chemical that will stunt your plants growth, break apical dominance (The plants ability to grow up)
You should learn all the ways to control canopy height.
Right On. Read everything you can. I got a big note book I used to write down everything important.
The more you put into it the better your results will be.