SEO Meta Title and Description are basics and MUST HAVE settings for your website.
For adding those you must put below between <header> </header> tags in your HTML page like the codes I put for my website:
<title>Tips for Programming, Sysadmin, GIS, SEO | Full Stack Logs </title>
<meta name=”description” content=”Full Stack Logs provides useful technical tips such as WordPress, Docker, Apache, MySQL, PostgreSQL, Tomcat, GIS, SEO for sysadmins, developers, GIS and SEO.“/>
For Google SEO it is really important to think about the title and descriptions and use the words which exactly tells google what is your website or web page is about.
You should also do some keywords research to find out what keywords are relevant for your website and try using them in the title and description.
You can also look at the other websites that you like and then find what is their title and description. Open their website in your browser and right-click and click on “view page source“, then search for “title” or “description” to see what are those values are. Make sure to look at the values before </header> since you might find title and description words more than once in there.
Make sure you ONLY have ONE title and description tags in your HEAD section.
Usually, Title Tags are 60 Characters and Descriptions are 160 recommended characters.
If your website is WordPress you can install AIOSEO Plugin and add the title and description in the Global Settings section like below.