There are plenty of Excel courses online, but first you should clearly specify (narrow down) your goal and make it realistic because it's absolutely impossible to "master Excel in 2 months" (to be a real expert in Excel will take many years).
On the very basic level you should focus on Excel Worksheet operations and menu navigation. It's realistic to acquire some basic skills within 2 months. Moving further to advanced level (upon necessity) you should learn VBA programming and probably Excel Integration into Windows app using more sophisticated languages like C# or C++ in Microsoft Visual Studio.
Hope this may help.