There are various ways to create a PDF file. Generate a PDF quickly by using menu commands, dragging-and-dropping files onto the Acrobat application icon, or converting clipboard data.
To create PDF files or any document in PDF format, you have to subscribe to Acrobat DC, to know more about Acrobat DC and to subscribe, please refer to Plans and pricing: Compare versions | Adobe Acrobat DC
To know more about how to create PDFs, please refer to Create PDFs with Adobe Acrobat
Feel free to update this discussion for any further assistance.
Here is a tip: most people would just use Word. You do NOT use Acrobat to type a letter. Acrobat turns the letter into a PDF.