Hello, I would suggest using a automated script as you are not familiar with the process. Here is one I found real quick on google: https://www.xml-sitemaps.com/
For xml sitemaps I work with (WonderWebWare SiteMap Generator) software, it's free, scan unlimited pages and easy to use http://wonderwebware.com/sitemap-generator/
For software, you can also look into GSiteCrawler (free) and A1 Sitemap Generator (paid) or try search Google for more alternatives and see which work best / most easy for you
There are many website which gives you .xml file for sitemap. You can easily download it by putting your website url over there.
There are many online xml sitemap generator. Search that site and create your sitemap as simple as that..
You can use https://www.xml-sitemaps.com/ too.. the result can be html, xml, or others.. Suggested by Google..
Do you only need to create standard XML sitemaps or also e.g. video sitemaps? And how large is your website?
You do not clear that which blog or site you are used if you used blogger then your site map will be atom.xml or otherwise in any cms site you need to generate site map for your website.
If your site is on wordpress than you use Yoest Plugin its very easy to use and generate good sitemap, also You use xml-sitemaps.com for generate site map
By using sitemap generator tool,you can easily create sitemap. Use the following link xmlsitemapgenerator.org
Through some online xml sitemap generator sites you can generate your xml file by putting your website URL or if you developed your website in wordpress then you can generate it to through simply a plugin.
There're many ways to create site map. Usually if your website based on Wordpress platform, you can use the plugin called Google Sitemap Generate or Yoast SEO plugin to help creating sitemap. Otherway, if your website is based on PHP or another platform, you need to create manually by using this webstie https://www.xml-sitemaps.com/. Just enter your website on that website and create. Hope this helps.
If you use Wordpress i recommend the plugin Google XML Sitemaps https://es.wordpress.org/plugins/google-sitemap-generator/ who generates the XML with a few clicks.
There are lots of automated software which you can use to create an XML sitemap. some of them are: XML Sitemap Generator Google Sitemap Generator WriteMaps Power Mapper and many more!