Have you looked in the Help file? It tells you to do the following:
1) Open Computer Management (Local).
2) In the console tree, right-click Computer Management (Local), and
then select Properties.
3) On the Advanced tab, click Performance Options, and under Virtual
memory, click Change.
4) In the Drive list, click the drive that contains the paging file you
want to change.
5) Under Paging file size for selected drive, type a new paging file
size in megabytes in the Initial Size (MB) or Maximum Size (MB) box, and
then click Set.
If you decrease the size of either the minimum or maximum page file
settings, you must restart your computer to see the effects of those
changes. Increases generally do not require a restart
hth