[Gretl-users] How to put together "names" with a number linked with to build an Index

Dear, greetings from Lucca, Tuscany. I got data from U.s.a. concerning the financial market. I have to order them in the specific sector. I have the name of stocks in column and in another one a number (ex. 20, 56, etc...) The number means the sector. I have to put together all the stocks with the same number to build the index of the sector. Anyone knows how I could do it with Gretl? Thanks, G. Simari