Only some aftermarket shocks have an adjustable valve. You most likely don't have an adjustment valve. List symptoms that make you believe you need better shock absorber performance.
Shocks.
Cars would use shocks or struts in front but not both.
You cannot. Stock shocks are not adjustable.
there are no adjustment less you have air shock
used to absorb shocks.
if you adjust the shocks.
About the only way is to adjust your shocks
ES 1000's are not adjustable .
The shocks on a 1999 Harley Fat Boy are not really adjustable. There are kits that lower the bike available on the after market.
All you can adjust is the preload. You need a spanner wrench. http://www.xs650.com/forum/
The front shocks are actually "forks". If you are asking how to adjust them to be more firm, that would depend on how firm you need to go. You can adjust the feel of your forks by a different weight fork oil, different spring or damper rods.
Yes, one at each wheel