BLAST page - look under 'Basic BLAST' heading for the standard types of query - blastn, blastp, blastx, tblastn, tblastx
There is plenty of additional information available on this site about BLAST and related programs.
Various Analysis Tools
Local Alignment Tool for 2 nucleotide sequences - note you must know the relative orientations of the two sequences. If your first pairwise alignment doesn't work, try one sequence in the reverse orientation.