carry forward of long term loss on sale of shares

Yes you can carry forward long term loss on shares to subsequent assessment years.

please help me with providing section

If the long term capital loss relates to shares, equity oriented fund, units of business trust & all conditions falling u/s 10(38) complied then u can't carry forward that loss coz that loss is dead loss. Otherwise i.e if u are not falling under conditions 10(38) then u r eligible to set off ur loss with short term capital gain this year & carry forward & set off with only long term capital gain in subsequent years.