Instead of downloading from source use the Package Manager - KPackage.
The book "Point and Click Linux!" by Robin "Roblimo" Miller deals with SimplyMEPIS. Chapter 24 covers Downloading and Installing Software.
First click the System Centre. Click on Package Manager. Choose "Use Internet". Click Apply.
Second click the K-Gear on your Control Panel. Go to the System submenu and call up KPackage.
Third, in KPackage click Special, chose Apt
ebian, chose "Update".
You shoould be able to see the Packages available and hopefully work it out from there.