Search engines find your content. Eventually.
A search engine usually finds your content via a link from another site. The search engine bot "crawls" the other site, finds your link there and then follows that link to your site. Other times you will submit your sitemap to your Google Search Console, which can trigger your site to be crawled.
So how exactly do you submit your content to Google if you don't submit a sitemap or have a link from another site?
Step 1 - Visit this link in your Google Search Console

You will need to be logged into your Google account to gain access to this page.
Click "start now"
Step 2: Submit your website's link

The easiest way to do this is to add your website link to the section on the right of the above image called "URL prefix.
Then click continue.
Step 3: Verify You Own The Site

This is where it gets a little tricky... You can add a HTML tag to the header to your site, or outsource this to your web person or web VA.
Or, if you have a Google Analytics account, you can use this and it will connect the two.
A button will appear and ask you to verify this. Click the button.
Step 4: Google Checks You Out...
And if you've added the HTML code properly you will see this screen:

When you see this screen it's important that you click "go to property".
Step 5: We're in your "property" aka your site on Google
You will now see a screen similar to below:

It's absolutely normal for there not to be much here, as the search bots are going over to your site and looking for your content. Give it 72 hours to make it's way around your site and get to know your content.
Step 6: Click URL Inspection
You'll find this in the menu on the left, 3rd one down... Then paste in your link to a blog post or page on your site. Your link should be to a live page or post on your website.

Then hit enter. Google will now test whether the live URL can be indexed. Assuming there are no errors, Google will submit your URL for indexing and you will be in a queue.

And that's mostly it!
Once your site is crawled by the search engine, it decides on where you content will sit. Just because a site is crawled it doesn't mean the page or post will be on the front page of the search engines. Over time the search engines get to know your content, and it will decide whether to send people to your posts and pages. You can help get your site indexed and ranked by creating your best quality content on the things your audience (ie your customers) would want to know about.
Is it normal for all my pages to be indexed by Google?
Nope, it's not.
This is what John Mueller from Google has said about Indexing in the past.
We never index all known URLs, that's pretty normal. I'd focus on making the site awesome and inspiring, then things usually work out better.
—johnmu of switzerland (personal)
(@JohnMu) January 3, 2018
Submitting your content to Google to get it crawled and then indexed is a great thing to do. Make time to submit a different URL each week. If the URL can't be indexed, Google will let you know why so you can correct the issue.
Pros & Cons of Submitting Your Content to Google
Pros:
Cons:
Conclusion:
Submitting your site to Google so that it can crawl your content is a must. This isn't something that a web designer will always do. Some don't set up Google Analytics for you, some do. Taking 20 minutes to sort this out for your website is time well spent!