How to Validate data in LSMW?

Hi Experts,

I got one requirement in LSMW. i need to validate text file data with database level table data.

information for my req:-

i'm using custom table.

text file contains lakhs of records. so i need to avoid select statement with in the records to fetch.

some more doubts.

1. How to assign TR to LSMW.

2. How to download/Upload LSMW..

3. How to provide selection screen in LSMW for file path in LSMW to above requirements, if it's possible where can i write this code?

Regards

Shankar B