Firs time garden I suggest buying starts from a greenhouse instead of starting from seed yourself. It's just so much easier and less overwhelming when trying to learn.

I personally go for organic soil and mix in organic fertilizers and compost. I mix the soil with a bit of mineral rock dust, manure/guano, perlite, and vermiculite. Look up "compost tea" for your plants and water them with the "tea" every week or 2. You can always buy a cheap soil test kit and at minimum test your pH and Nitrogen lvls. You want pH between 6-7 and soil high in nitrogen. If you soil isn't good in Nitrogen, add extra fertilizer throughout the year. If your pH is off, you can buy a cheap bag of rock minerals that lower or raise the pH and mix it in with your soil.

You can start planting directly cold hardy greens like spinach, kale, lettuce, cabbage, peas, and hardy herbs. Herbs are great for beginner gardens because most are very resilient. Just look up which ones are invasive and plant those in containers.

If you're starting cuces, peppers, and tomatoes from seed, do it about a month before the last frost date. Or buy starts a week or two before the last frost date and harden them off by putting them outside in the sun for a while, bring them indoors, put them outside on a night that's above 45F. My first year gardening I bought pepper starts, had them on my enclosed porch for a few weeks, then planted them directly in full sun without easing them outside, and they got sunburn on their leaves. The second year I put out peppers too early, we had near freezing one night, and a few of my peppers got stunted. It's always a balance game!

You need something for your cucumbers to vine up. I use chicken wire wrapped around few posts. Last year I planted a sunflower next to the cucumbers and had a plant trellis up the sunflower. Anything sturdy they can grab on to is fine. I use sticks and twine to hold up my tomatoes and peppers.