Installation of Skype requires a little bit more work since it is closed-source proprietary software. It can be found in the Ubuntu Software Center only if the "Canonical Partners" repository is enabled. You can do this in many different ways: https://help.ubuntu.com/community/Skype The easiest way for you is via the Ubuntu Software Center -> Edit -> Software Sources. There you have to check the box next to "Canonical Partners" in the "Other Software" tab. Btw your problem with typing in the terminal (at least from the scarce info that you have given us) does NOT seem connected to Skype itself (since it is not even installed on your system).
A piece of advice: don't just write any command you find on the internet even if the one who posted it states that it IS the solution. Always check and double-check. Also when you post a question like this without giving ANY useful information the probability that you get a (quick) reply decreases a lot. When you say that you have "typed in some command" the people who come here to see your question in detail with the intend to answer it start scratching their heads "What command? Where did he/she find it?". Frankly I needed to read 2-3 times your question in order to (maybe) understand what you want to do, which omho is a waste of time (my time at least).