Hi,
First, sorry, by move I understood moving them around, place them elsewhere
in the sequence of tasks.
I now understand you want to change their start dates.
I can't but insist that that is not normal usage of Project, but anyway.
I suppose you want to place a start no earlier than constraint?
In that case select the tasks, click the Tak Information button on the
toolbar, and set the constraint.
OTOH, if you want to set a constraint based on "their current start date
plus a certain number of days" you will need a small VBA procedure.
Hope this helps,