Can I use more than one mod on minecraft?

I currently have two profiles for minecraft 1.7.2 on mac. I have installed 'too many items' manually as there isn't a forge version yet and this is the only mod I have used. I want to in the future download and use Zan's minimap. Can I do this whilst keeping the 'too many items' mod? How will I do this?

Yes you can. Simply install the mod just like you would with any other mod. Some mods will not work with each other and won't allow you to even launch the game but thats rare.

Yes you can install more than two mods but I personally prefer rei's mini map. And if you do like mods in minecraft I recommend downloading the latest technic launcher to get mods in minecraft because its alot easier to do

Assuming the two are compatible, yes.

Some mods aren't compatible, they use the same block ids or things like that and get into each other's way.

Other than that you can use as many mods at a time as your computer can stand. Some mod pack have 60+ mods at once!