Usually, when too is used at the end of the clause, it means 'also' or 'as well'. So, also = too in that way.
When I've finished painting the bathroom, I'm going to do the kitchen too/also/as well.
The preposition 'to' is entirely different. Don't use it to mean 'too/as well/also' in any case.
'to' has many meanings and usage. Refer any dictionary too to find that!