there is a dummies way [not intending any insult as i use it myself occasionally]
you have your bootable ISO on a pen-drive, Now get another good branded one of at least 64 gb and pref usb3 [blue insert in connector]
put the ISO in the primary USB port [normally the one nearest the power supply if its a laptop] and the new usb in a spare point, now switch on your machine whilst tickling the one time [short] boot key], select the ise with the pen drive and run as you have been, now depending on the distribution click on the install icon [AND FOLLOW the instructions in my signature] EXCEPT when it starts to install it will open a screen with the driver and partitioning, click on the drop down box and find the new pen-drive and select, now, select use complete drive and ok/install, provided you have selected the correct destination for the new pen-drive, it will install to it, as if it was an SSD or old fashion plate spinner,
this is a great way to carry your own computer with you as you will be able to boot it from most compatible machines, BUT BE AWARE use a good quality pen-drive for maximum life, as they do burn out quicker being used in this way