For my garden what is a good addictive to add to enrich my soil?

https://www.thespruce.com/making-good-soil-out-of-bad-1402428

It depends whether your soil is clay, acidic etc and what you're planning on growing, if it's clay then roses will do well you can add bonemeal. If it's very acidic you could grow Azalia, heathers etc. they like a top dressing of Ericaceous compost. Good luck enjoy your garden x

Get a 5 gallon bucket with a lid. Pu it in a place where small will not bother you. Over the winter dump all your raw vegetable scraps in the can - shavings from carrots, wilted lettuce, potatoes peelings etc. No meat, nothing cooked. By March or so, you will have a liquid mash. Mix this very well into your garden 30 days or so prior to planting. Will bring tons of worms. It will kill any plants there as it is very strong. But after 30 days it will calm down. Very STINKY. But it will produce! AND it is free.

BlackCow manure soil. Sold in just about any big box store. Works great! Just mix it in with your soil.

The previous answers have contained the solution: adding organic matter improves any soil. Loosen the soil down about a foot then mix in plenty of compost, aged manure, or any other material. Most garden stores now carry bags of organic soil amendments. Begin every Spring by mixing in another few bags.

If you are worried that your soil needs amendment and it's just not there, you may use straw bales this year or container gardening. Look up Straw Bale gardening or Container Gardening on You Tube for details. Next year you will have the used straw to mulch. I used straw bales this year and I had a very good harvest . Meanwhile, start a Lasagna garden. Look it up on YouTube also. It's just a simple layering technique to make compost and you don't need to till the soil. And you can plant directly on it depending on the composition/layer that you made. Try these and see what works best.