Yes, The Standoff Screw Comes with the motherboard.
The stand-offs and screws come with the case, not the motherboard Since you are new…. Make sure you use the stand-offs that came with your case, do not mount the motherboard directly to the case without using the stand-offs!
Yes, standoff (or support) screws do come with most if not all motherboards. These screw holes usually are located on the back of the ATX or mini-ATX style motherboard form factor. Sometimes there is only one hole for standoffs, sometimes there is a whole set of threaded holes with accompanying screws that you can use. If you did not get any stand offs from your manufacturer or case maker then you will have to purchase some separately or you can use a regular wood screw.
The width of the screws is very important because you need to make sure that they will not interfere with any expansion cards or memory modules after installation. In some cases these standoffs are used as mounting points for heatsinks on the back of the motherboard, so if there is an empty standoff hole in your case just remember that it could be used to mount components other than just support hardware for the motherboard.
If there is only one standoff hole on your case then I’d advise putting all of them into that single-threaded hole; just try to spread them out evenly as much as possible across the board and do not put more than four total (two sets) of standoffs in any given socket/slot. If you have more than one empty threaded hole and/or stand-offs, then I would put them evenly into the various holes throughout your case.
Again; try not to put more than four (two sets) of stand-offs onto any given motherboard or expansion card slot. This will allow adequate room for air circulation around the components on your motherboard as well as keeping the circuit boards from damage due to excessive pressure by metal screws.
Also make sure that you do NOT overtighten these screws. They’re only there to keep your motherboard in place while installing it into a case or another device later down the road after installation is complete, so how tight they are does not matter unless otherwise instructed by the manufacturer of your computer hardware or an after-market case maker.