You can use two ways (sort of):How do you find the range of secondary structures in Jmol? Like this sheet is from this amino acid to this amino acid this?
1) Find the sequence sheet from the protein database and look at when the secondary structure end and start
2) Color secondary structures on Jmol and then hover your mouse over where the structure starts. Eventually a white box should appear and it will tell you the number sequence. You then do the same for end too.
Just to note you have to use method 2 during the onsite build because you cannot look up the sequence sheet. If you need anything else PM me.