I agree getting them done at the salon initially is a good idea to get them into shape. Then trim them at home if you want. If you don't want/can't go to a salon, try -
Use an eyebrow brush (like a mascara brush) to brush eyebrows upwards. Use a small scissors to take the longest ends off. You might have to hold the hairs in place with the brush while you cut (or brush soap on to keep them in place). Brush again. If you're not sure what to cut try drawing in your eye brow shape with a makeup pencil and trim away the excess. If there are curly ones don't pull them out, find where they curl and snip the curly bit off. I do this about every two or three weeks using a huge magnifying glass and my glasses and a bright light so I can see what I am doing. Don't keep doing one eyebrow before starting the other incase you have to stop before you complete them, and end up with two different eyebrows 🙄