get out your handy dandy air erase pen decide where you want the design, drawn a line for the bottom of your design, then line up the bottom inside edge of your hoop with the line you drew and poof you're right on target.
great Question i am always nervous when doing this for others hugs
I print out the design so I can see where it will be, then I mark with a wash away pen the center & the lines both vertical & horzinal on the fabric. Then I make sure there's some room all around the design in the hoop. My machine has a feature where I can find the middle of the design & move the design up/down/left/right to get the center I've marked right in the center of design. Apply, go back & stitch. If you're machine won't do this, then try to line it up with the lines on your hoop. You can also mark the center & not hoop the fabric-just the stabilzer- & set the hoop to go to the center so you can line it up that way. BUT you get a better stitch out if it's hooped, if it's a material you can hoop. Am SURE ELibrary will be a lot more clear than I am!!
This is a very good question to ask. We all can remember project(s) we struggled with. EL is a wonderful resource for any of our embroidery questions. And all of the tutorials are free. I keep the EL page bookmarked for these reasons. Don't hesitate to ask a question that has been asked before. We all can use a refresher now and again.
Go to Embroidery Library. They have videos and projects that show you step by step with illustrations how to. Hope this helps.
Rachel