add shortcode

1) my theme using post ( and those post have longitude and latitude) with the longitude and latitude we give postion for the post on the map, i want to create shortcode, that will use it just for mobile and trablet ( i am using redirect for mobile and tablet) so the shortcode will take the current postion of the user and show the item that are near by ( according to categroy and range ). the user will select categroy and range of kilometer, and type search to found items nearby. to show 5 items just, and then show another 5 .. i want it to be fast , as my website is very fast. we done it on one page, so to do the same, but reading the postion of the user.