Do you mean that you wish to change the contents of the file to contain only uppercase? If so, my (very high level) suggestion is:
First, rename the original file
Rename <origName> to <backupName>
Open the text file:
Open <backupName>For Input As #1
Read the contents into a string variable
<string> = Input$(LOF(1), #1)
Upshift the variable
<string> = ucase(<string>)
Close the backup file
Close #1
create a new file with original name
Open <origName> For Output As #1
write the variable to the new file
Print #1, <string>
close the new file
Close #1
optionally delete the old file
Kill <backupName>
I hope that's of some help...
Phil