How do I become the executor of a will?

With your father's declination to act, assuming that he is of sound mind and able to understand and communicate is desires, you should be able to file a petition to admit the Will to probate and request the court to issue "letters testatmentary" to you as the executor, which is your authorization to act. Until the letters of office are issued by the court, a person named as executor does not have the authority to do anything other than direct the disposition of remains and burial, pay funeral charges and preserve the estate. (Section 6-14 of the Probate Act). A petition to admit a Will an/or for the issuance of letters testamentary must include all of the information required in Section 6-2 of the Probate Act. There are many things that an executor is obligated to do and procedures an executor is obligated to follow. This answer is not intended to create an attorney/client relationship and is not intended to be legal advice to you in your specific situation. It is a general statement of the law responsive to the few facts you stated and the question you asked. You should consult a local attorney who has a good reputation in your area and who handles probate estates.