Before beginning any pracitce make sure your computer has version 3.5 of the Microsoft .Net Framework.  It's a free download from Microsoft and necessary to run the practice programs.  Click this link to run a file that will check what version your computer is running and if it is necessary to download the newest version. 
.Net Version Detector

After you run the file, if you see 3.5 in red, then you do not have the most recent version.  Just click on the arrow button to download the newest version.  You will be directed to Microsoft's installation page. 

Solving Two-Step Equations

Solving Multi-Step Equations

Integers and Powers ( Mr. Nuth )