Forms and keep forms data within post-type

Quite a newbie question:

I have some custom post types called “Workshops”.

How can I set a form, for any user, for subscribe for those workshops?

Steps
*Frontend:

• Visitors check the open workshops (post type)
• Visitors view a workshop and clique a link “Subscribe”
• The page (a page) shows a form for subscription. The form is the same for all workshops

*Backend:

• The post-type (an workshop) keeps the subscribers data
• Can export the subscribers list in excel

Is that too much? I tried some plugins, but I don′t need any paying system. Just need the form and keep the data within every post-type. I don′t understand how forms can work in WordPress, I see lots of plugins for that, is that too hard?!

Thanks for any help!