First, I would advise you to know very clear what you want to include in your membership site (will you have free level? Basic level, “upgrade levels”, etc.)
Based on this you can decide which membership software will best suit you needs. You have mentioned blogging so maybe WordPress and some WordPress membership plugin would be good choice for you.
Transferring data from old to new membership site can be very time consuming task. I would recommend you to outsource this task, especially if you are not a technical person.
I learned this myself…the hard way. I once spend two weeks editing and polishing my membership site. Then I found someone who did the same job in 2 days.
It was not total waste of time for me because I learned a lot during that time…but still…it did leave bad taste in my… memory 🙂