I work with RNA as little as possible in the laboratory and this holds true for software analysis as well.
RNA File Types: RNA sequences,like DNA sequences can be contained in different file types. The more complex would be an RNA trace file. The simplest, and most common, is a text file. Most RNA sequence files are text files. At the simplest, there is just RNA sequence. The more complex text files contain comments and other data.
Text File: (*.txt) The simplest type of DNA file, containing only DNA sequence as IUPAC letters; no numbers or symbols. This type of file can be edited by Notepad (or Notepad++) or other word processing programs. Make sure to save as a TXT file to avoid inclusion of other style tags. Example DNA sequence as a text file
Fasta File: (*.fq, *.fa) This is a straight text file. The first line of the file usually begins with a greater than sign (>). Any text between this symbol and a hard return is considered description and will not be included in the sequence. The RNA sequence is typed after the hard return.
When I find the time I'm going to have a page that's just file extensions, file descriptions and links to converters. MEGA is a good converter and works on Windows 7, 8 and 10 operating systems. BioEdit (while very old) is an excellent converter although Windows 7 users may have to run the 16 bit application readseq in a virtual XP window. Seqverter is another good file converter.