SQL Command Help

Friend helping me learn...

Asked... Am I right in my thoughts...

1)  If Exists(Select * tblOne) Begin
     Update tblOne set field1 = 'true'
     End

Problem is  Missing FROM on Select?

2)  Insert into tblOne value (true, not burned)
     Select @@ident
     Update tblTwo set mgr = yes, Qualified = yes

Problem is yes not defined ?  NOt really sure about intent, maybe a true?

3)  Declare @count int
     Select @count = Count(totalNum) from tblOne where cooked='Rare'
     If count = Begin
     Update tblOne set MgrFlag = 'true'
     End

Problem is If statement needs a condition  like   If count = 1 Begin

4)  Merge tblOne
     Using tblTwo
     On (tblOne.brand = tblTwo.brand)
     WHEN MATCHED
     Then Insert into tblOne values('true' , 'not burned')

Syntax correct but will insert put data in 1st 2 fields of the table?

Any help appreciated