Main problem is laptop is booting up with welcome screen but not loading windows 10 , so how can I use seatools for it and what I have to do to install it. I am not getting it.
I don't think you need SeaTools if Windows is booting as far as the Welcome Screen. If the HDD was beginning to fail I doubt the boot process would get as far as that.
If you still want to test the HDD though, you can download the ISO for "SeaTools for DOS" from here:
https://www.seagate.com/gb/en/support/downloads/seatools/
You don't install SeaTools for DOS, you create a bootable CD or pen-drive from the ISO file, then boot your laptop from it.