Excel is an extremely powerful and extensive software application. To really be proficient at it you should be skilled in a variety of aspects of the application as depicted in this graphic:
Greg Truby, the author of Truby's Toolbox, has trained hundreds of business professionals on Excel. Greg has developed extensive training programs on each of these key aspects of Excel and would be more than happy to help your team improve its Excel skillset. For detailed information on professional Excel training available, please visit the training page on Greg's website.