I need a random number within a range, and not to duplicate the numbers in current list

Could I create a button to insert the data into the spreadsheet. I could create text boxes for SchoolName, Fname, LName, GR and maybe a check box for "is currently enrolled"?
I don't want to ask for tooo much, but would you know the code to insert that data in the current spreadsheet??

Would I have to change the lblGenerate to a textbox so the data can be inputed into spreadsheet?
Other than that I have:
txtFname - Last Name
txtLname - First Name
txtGrade - Grade Level
chkEnroll - checkbox for enrolled
cmdSubmit - submit to spreadsheet (assuming where the code will go)