I'd suggest web and literature search with relevant keywords (e.g. "non-coding, rna, prediction"), read, then come back here when you have a more specific query.
noncoding DNA are genomic sequences that do not encode for a protein sequence
noncoding RNA are functional RNA molecules that are not translated into a protein.
junk DNA are the genomic regions that are the remnants of the iterative evolutionary process and have lost all biological function,
Occasionally some use the term 'junk' too liberally describing with it everything that is unknown to them.
Noncoding RNAs are found by extracting and identifying (for example via sequencing) the RNA present in a cell and comparing that to the known protein sequences.
Coding regions tend to have longer sequences without stop codons. Additionally, the codon usage frequency table tends to follow some frequency table, typical to that organism. Start of transcription can be detected by relative nucleotide frequency. These multiple algorithms are combined into finished tools like GenScan that you just need to use in most cases.
I'd suggest web and literature search with relevant keywords (e.g. "non-coding, rna, prediction"), read, then come back here when you have a more specific query.
Ohhh .. I hope I ll do my best on my next query. Many thanks for your guide. :)