If you are in the internet, you can go to NCBI Blast and select the EST database..
Then, using megablast or dc-megablast run your comparison
If not hits are obtained, then you can make a search in the SRA database. If hits are found for the citrus genome, then you can write down the accession SRA numbers, and go again to the NCBI to select those databases (in this case the latest option of the databases is the SRA database itself)
If not internet connection is available thing are pretty much complicated. You need to run your search locally, but you need to get your programs and data from the internet
Somehow look for the blast+ programs that can be downloaded for unix, Mac and Windows systems
Look for the sratoolkits. Read a little bit about it. There is an option that allows you to run megablast and dc-megablast locally (in your own PC) with the same SRA files you download from the SRA database. Not need neither to create FastQ or Fasta files, not to create a database with these files. Is pretty simple
If you have your own data. then you can run blast locally creating a database with makeblasdb, and then define with task what you want to run with blastn (megablast or discontinuous megablast), etc
What do you actually want to achieve - citrus ORF identification or something else?
I want to find the key genes involved in a specific pathway, by blast and keyword search against EST database then blast the result against genebank to filter the results