I went through a similar problem, heres what i did. Download ASUS backtracker. Plug in a usb flash drive, let it copy the files to the flash drive. Shutdown. Take off back cover, remove HDD, put SSD where HD was. DO NOT PUT BACK IN THE HDD.... yet. Put cover back on. Go to bios pick usb flash as boot device. It should put the default files and partitions on ur SSD. Basically it takes the factory Images from the HDD and puts them on ur new SSD
I bought a USB 3.0 to SATA cable to hook my HDD to it to reformat and use as a storage drive. sometimes if u try to boot a computer with 2 HDDs with the same OS files it corrupts one of them. So i wouldnt put the hdd back in until you get the cable. I wanted to put OS on my SSD as well. I got a PNY optima thjng runs perfect. but this is what i did to get mine working. After it copies the files youll notice that there is 2 partitions. one named OS and another bigger partition cant remember what is was named. but if u want the WHOLE SSD for OS, go to disk management and choose EXTEND VOLUME. Pick the rest of the MBs and BAM all the space on the SSD is for OS. Hope this helps