How to make sure cat uses his shelter?

There are about 7 feral cats live in my house yard. I'm thinking of building a shelter for them. like this one https://petsfurkeeps.files.wordpress.com/2014/01/coolershelter.jpg

also a tent but I'm afraid no one will use it. 

If its cold or rainy they will probably use them.  You can put smelly food in to lure them.  Also catnip.

Food may not be a good idea - it might attract other critters.  But catnip is a good idea.

I've made shelters using these coolers and they really work.  They are nice a cozy - you just have to make sure the rain doesn't get in.  A tarp over them will work - or a tent, as you suggested.

I would just make sure you make enough for everyone.  Some cats may not mind sharing; others may want their own space.

I had to feed mine a couple of times to get them to go in the shelter the first time.  I took the food out after I observed them leaving.  I definitely wouldn't leave it in there overnight but morning feedings work well.  They are really hungry.

Thank you so much for your input everyone. will def try out the suggestions. Thing is where I live its extremely hot (115~118 F). Summer season is a lot longer here and the winter is not even that cold(rainy days here and there). I feel very sorry for the cats. Its unbearable that they disappear from morning to afternoon.  I'm not sure how to make the shelter cool? maybe place a cooling gel pad inside?  

Cats are descendants of desert animals...as long as they have shade and cool water, they seem to do okay.  Shelters such as you posted are only necessary to protect them against the cold.  The straw acts as a body heat insulator.  I have some cats in an outdoor shelter that is shady.  They have a water fountain that is stocked with ice cubes on hot afternoons.  They don't do anything but sleep in the heat but such is the life of a lucky cat.

Dandila said:

 
I had to feed mine a couple of times to get them to go in the shelter the first time.  I took the food out after I observed them leaving.  I definitely wouldn't leave it in there overnight but morning feedings work well.  They are really hungry.

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This is true.  As Dandilla says, use it sparingly and don't leave it if it doesn't get eaten within a few hours.