You insert all of it where you want the result to appear. It will show those fields and their leading texts where the values are greater than 0
{ IF { MERGEFIELD "Field Name 1"} > 0 "Field Name 1: { MERGEFIELD "Field Name 1" \# "£,0"}
"}{ IF { MERGEFIELD "Field Name 2"} > 0 "Field Name 2: { MERGEFIELD "Field Name 2" \# "£,0"}
"}{ IF { MERGEFIELD "Field Name 3"} > 0 "Field Name 3: { MERGEFIELD "Field Name 3" \# "£,0"}
"}
You can use
Import and export field constructions as text if you wish to convert the text above to fields (change the text as appropriate)