[Grammar] How to express possession of someting?

[JustAlilBit]

How to express possession of someting? I mean when do I need use " is - 's and of" ?
For example:
Gift's bag or Gift's bag or Gift bag ?
Maybe possesstion has any rule?

 

[bhaisahab]

How to express possession of someting? I mean when do I need use " is - 's and of" ?
For example:
Gift's bag or Gift's bag or Gift bag ?
Maybe possesstion has any rule?

What is a "gift's bag"?

 

[JustAlilBit]

What is a "gift's bag"?

The gift bag is stuff where we put gifts.

http://www.sizzix.com/images/ideas/large/951.jpg?1305126945

 

[bhaisahab]

The gift bag is stuff where we put gifts.

http://www.sizzix.com/images/ideas/large/951.jpg?1305126945

That's a "gift bag". A gift doesn't possess the bag that it is in.