Calculate date from differente form

Calculate date from differente form

I have a table1 with this field

course updateday (days)
rls           365

table 2
name - course - date course - date update
Jhon       rls          1/3/14          1/4/14

I need to insert  a field /date update)  in the table2 that calculated in automatic the new date of update
How to made it?

Best regards?