surf the Net/Internet
You can find all kinds of information on the internet.
Sam went into the kitchen to make a pot of tea.
She is in the kitchen making a meal.
I'm not sure about 'surfing a forum' but here are some wikipedia examples:
Poor understanding of differences in values of the participants is a common problem on forums.
Rules on forums usually apply to the entire user body.
One common faux pas on Internet forums is to post the same message twice.
Users sometimes post versions of a message that are only slightly different, especially in forums where they are not allowed to edit their earlier posts.
send private messages in the forum.
visit the forum
Occasionally an administrator will disallow visitors to read their forum as an incentive to become a registered member.
And some information on how to use in/ on/ at:
IN
France, Paris
the kitchen (rooms)
a shop, a museum (buildings)
a park, a garden (closed spaces)
a car
February, June
winter
2004
morning, afternoon, evening (NOT night)
ON
a bike, a bus, train, plane, a ship (NOT car)
the floor, a table, a shelf, the balcony, the roof, the wall (surface)
March 1st (dates)
Tuesday, New Year's Day, Valentines Day (days)
AT
wchool, home, work, university, the airport, the station, a bus stop, a party, the door
6 o'clock, half past two
Christmas, Easter (festival periods)
night
the weekend