Hi,
You may follow the steps given in below three links.
Third link is specifically for Task List LSMW but you need to follow Part-1 and Part-2 also for basic steps.
LSMW for Master Data upload Simple Explanation (Part - 1)
LSMW for Master Data upload Simple Explanation (Part - 2)
LSMW for Master Data upload Simple Explanation (Part - 3)
You may start with Part-3.
Hope this may help.
Chin2.