These networks differ from regular social media (Facebook, Twitter, etc) in that they are specifically targeted towards sharing your professional and scholarly accomplishments.
Academia.edu and Research Gate are specifically tailored toward sharing scholarship, and help you monitor analytics around your own scholarship as well as follow other scholars.
1. To set up an Academia.edu account, you can link it to your Google+ or Facebook accounts, or if you would rather do it via email, that is also an option. You can easily upload scholarship, link your IR account, and follow colleagues. Be sure to upload a profile picture!
2. To set up a Research Gate account, you can easily set it up using your email, but the account can also be connected to your LinkedIn or Facebook accounts.
3. LinkedIn can also be created using your email address.
It is worth noting that these sites are commercial, meaning that there is always the potential they could change, disappear, or lose credibility over time. To cover your bases, we recommend always having your profile in the Institutional Repository as well.