Should I have one reverb for my entire mix to give an over all ambience and then have separate reverbs for individual sounds to make the front the middle and the back and have some other reverbs for my parallel busses?
Also, I know that for low frequency elements you have to pre and post eq the reverb but what type of reverbs are usually good?
kicks?
Synth Basses?
Subs?
808?
I have watched cubase mixing and all the mixing and mastering program videos but still confusing
I’m not the expert you are probably directing this question to, but almost never, ever, ever, would you have a reverb on an entire mix, unless you were going for something quite specific (creating the illusion of a whole band playing and recording live in the same space, etc.). iZotope’s Ozone had a “Reverb” module, which many people wondered about why it was there (in a mastering plugin), but they’ve removed it now, if I’m not mistaken. No doubt somebody will correct me on this if I’m wrong 
I use quite a few reverbs, the key is to make them all relate. I will often use similar settings for sounds that are going to be in a similar space but modify them to fit that particular sound.
Sorry it is a vague answer but every project seems to be different. Sometimes you can utilise one reverb for all synths etc and it just works perfectly, another great for all FXs, a tighter one for drums and a couple of individual ones for snares, kick, bass etc.
Ambiance and early reflections only are the best for low frequency material in my opinion.