You're in for a ride! 
I had never heard of those PAs, but I've used a neat site where people help out and I think it has a lot of pre-existing material that should help you: https://artofproblemsolving.com/
The community area is huge, it's tremendous, it's awesome. You'll love it.
Then you have good old Wolfram Alpha... this will give you step by step resolutions of whatever you throw at it... not sure about proof of theorems, as I've never thought of using it for that.
https://www.wolframalpha.com/
I had never heard of those PAs, but I've used a neat site where people help out and I think it has a lot of pre-existing material that should help you: https://artofproblemsolving.com/
The community area is huge, it's tremendous, it's awesome. You'll love it.
Then you have good old Wolfram Alpha... this will give you step by step resolutions of whatever you throw at it... not sure about proof of theorems, as I've never thought of using it for that.
https://www.wolframalpha.com/
