Command block illogic

First bracket after "@a" is wrong.

on the wiki it says if you do there "< >" its a required command while "[ ]" is optional.

Correct, that is how you identify parts of the command, not what brackets should be placed in the command.

ok then should the command be written like this then: "[x=18,y=39,z=8,r=100,<team=Blue,score_Name=300>]" or is that still wrong?

It would be:

testfor @p[x=18,y=39,z=8,r=100,team=Blue,score_Name=300]

When angle brackets < > and square brackets [ ] are listed in a command usage, like...

testfor <player|entity selector> [dataTag]

...they just mean player or entity selector is required, and a dataTag is optional (like @unknown said). But keep in mind, those brackets have nothing to do with what brackets go on the actual command. It's just an abstract thing, telling you what's required and what's not.

To be clear, two things: a real command never has angle brackets, and your command has no dataTags. A dataTag would be surrounded by curly brackets { }. Your command has just the player selector, and a selector is allowed to have square brackets, which yours does.

I do: "testfor @p[x=18,y=39,z=8,r=100,team=Blue,score_Name=300]" and even if score_Name doesn't = 300 it still says it found me, check first screen shot

@Ricardo, the first screenshot obviously says that it found you, what's the problem?

"score_Name=300" means score of 300 or lower.

thanks you sir you have fixed the problem 😃