Solved my own mistake.
Had to download openjdk-6-jdk on linux (linuxmint) by using
sudo apt-get install openjdk-6-jdk
Then assigned the correct jarsigner, found at "/usr/lib/jvm/java-6-openjdk-amd64/bin/jarsigner" in the export edtitor.
For the .keystore file, I just used the command
keytool -genkey -v -keystore debug.keystore -alias resonance -keyalg RSA -keysize 2048 -validity 10000
On the .android folder.