try like this
FOR i=0 to NoOfRows('yourtable');-1
if i>0 then
FROM [http://hrapps//humanresources/hrwebservice/emplogin.asmx/Search?LanID= '$(vUserID')] (XmlSimple, Table is [DataSet]);
You could loop through the table which contained your UserID like sasiparupudi1 had suggested - also possible might be a loop through the field per fieldvalue() which is general faster but you will need bigger datasets to notice the differences.
If you want use FOR Each LnID in UserID the UserID needs to be a variable which contains a list like:
'User1', 'User2', 'User3'
and which could be used like: FOR Each LnID in $(UserID)
Such a listing could be created per concat() in a previous load and then per peek() assigned to a variable.
Therefore several ways are possible and the easiest way seems to be to loop through a table but if there are further requirements this could be change.