I have requested some bitcoin from my friend and gave him the adress that is displayed in the "receive" tab in the electrum client. After he sent them, I made a request for that amount in electrum and it is apparently "paid", as you may see below. However, it does not show up in my history as an incoming payment. How do i get it to show up there?
Always when in doubt, check online block explorers (at least two as all of them are buggy to some extend and might freeze for some hours/days):
...is your transaction there (you can search for your receiving address)? Is it confirmed? When it is not there at all you know it is not problem with your local wallet. If the tx is there you have probably problem with synchronization of your wallet - you can try to select different server to connect to (in Electrum's settings). You can also try running Electrum with different directory ('-D' command line parameter) to force it to download its metadata again and recreate your wallet from seed. You can also try to install Electrum on different machine & restore your wallet there. Maybe check your firewall, too.
What color circle icon do you see in the bottom right of the electrum window? If it's not green or blue try switching servers.
Also what version of electrum are you using? Old versions had problems syncing so I suggest using the latest version.