Insert Contents Of Text Box In Row / Column Intersection?

I have a large spreadsheet that has row and column headers. I am trying to build a user form that will basically have a row combo box (already populated with the row headers), a column combo box (already populated with the column headers) and a text box. I need what ever I type into the text box to be inserted into the cell where the row of what I pick in the row combo box and the column of what I picked in the column combo box intersect.

For Example:

If I pick "Apple" in the row combo box which is in cell B1 and "Red" in the column combo box which is cell A4 to insert what ever I put in the text box into cell B4.