Hey, you can totally do this :)

Put the item in a box and make sure it's secured really well. Get some packing tape, or any tape I guess and wrap it up. You can get a box from anywhere you like.

You can write the address on the package, or on a piece of paper and stick it on.

Go to the post office and tell them you'd like to send your package depending on your preference- whichever class you'd like and tracked/not tracked. You might want the person receiving it to sign for it.

You might consider putting a small 'if undelivered please return to.....' label on there too.

The member of staff will take your parcel, weigh it and calculate the postage. You can ask for a receipt if you want one. If you want it tracked they'll give you a number too.

All no fuss and simple, but I know not necessarily easy because anxiety is rubbish.

Hope that helps, happy to answer any more questions (or be corrected if I got stuff wrong). Again, you can totally do this.