Frequently Asked Question:
How Do I Type Irish-Language Characters?
How to type the following characters on a US-English PC: Hold down an <Alt> key while typing one of the following numbers on the number keypad of your keyboard (your NumLock must be on). After you finish typing the number on the number keypad, let go of the <Alt> key.
Irish vowels: á 160 Á 0193 é 130 É 144 í 161 Í 0205 ó 162 Ó 0211 ú 163 Ú 0218
Macintosh users: press <option> and e simultaneously, then let go. Then press the vowel you want the accent on, either lowercase or uppercase.
Other special characters which occur at least once in this database: à 133 è 138 ê 136 î 140 ö 148 ù 0249 ü 129
You can practice typing these here:
Note: many computers outside the US simply include these accented letters on the keyboard, so this procedure is generally only needed in the US.
My recommendation of an Irish-English dictionary: Fócloir Poca