How can I estimate the Half width at half maximum(HWHM) in the half of the Loren

How can I estimate the Half width at half maximum(HWHM) in the half of the Lorentzian lineshape for only ‘C’ sheet (very first page in the Excel)  using the Excel Solver?
The Excel sheet is attached. 
Please get the HWHM value directly into the Excel spreadsheet. 

"Get 15% discount on your first 3 orders with us"
Use the following coupon
"FIRST15"

Order Now