Switch statement and hash table

All,

I had a question in regards to the switch statement and hash tables.  I know with a switch statement you can do an array like so

$a = 21, 38, 6

switch ($a)

{ 1 {"The color is red."}

2 {"The color is blue."}

3 {"The color is green."}

4 {"The color is yellow."}

5 {"The color is orange."}

6 {"The color is purple."}

7 {"The color is pink."}

8 {"The color is brown."} }

I actually have found an example that I use to evaluate a hash table based on the $_.name value

$myHash = @{}

$myHash["a"] = 1

$myHash["b"] = 2

$myHash["c"] = 3

switch ($myhash.GetEnumerator())

{ {$_.name -like ‘*a*’ } {"It is a"} }

What I want to understand is how does the curly braces know to do a comparison on the $_.name variable?  How come you don't have to use the Where statement?  I didn't find any documentation on the swtich statement that went over hash tables.  IS there an advanced guide for powershell on syntax for things like this?

Also, is there a good powershell forum out there?  google only shows technet and I'm not a big fan of that format.