"So how I can find out the real guru by whose words I'll be nicely directed and achieve?" That is not very difficult. You read Bhagavad-gītā. You'll understand. Just like Arjuna. When he was perplexed, he accepted Kṛṣṇa-guru. He said, śiṣyas te 'ham: (BG 2.7) "I become Your (disciple) now... We are talking friendly. The argument will not be ended. Now I become Your disciple." Śiṣyas te 'ham. Because as soon as one becomes a śiṣya... Śiṣya means under the order, regulation. A person cannot disobey the order of guru. Then he is śiṣya. If he argues, he's not śiṣya. He's not a śiṣya. Therefore Arjuna says, śiṣyas te 'ham: "I surrender, voluntarily surrender to become Your disciple. Now I shall not argue." That is called śiṣya. If you argue, then you are not a śiṣya. Guru-mukha-padma-vākya, cittete koriyā, āra nā koriyā mane āśa **. This is tapasya, that "I shall not act anything which is not ordered by my guru," that tapasya. Tapo divyaṁ putrakā (SB 5.5.1). Then we'll be nicely guided, and then sattva śuddhyam... Then our this existence will be purified. And as soon as our existence is purified, then we realize the situation, what is God, what is our relationship with Him, what is our activities, athāto brahma jijñāsā, janmādya asya yataḥ, everything.
Here it is, tu ātmani īśa bhuvi. So what was the realization of Brahmā after tapasya? Now, gandham iva atisūkṣmaṁ bhūtendriya. Just like Kṛṣṇa says in the Bhagavad-gītā, puṇyo gandhaḥ pṛthivyāṁ ca: "I am the smell within the earth." So everyone knows there is smell within the earth. There is color within the earth. Everything is there within the earth. Otherwise how in a particular plant the color and the smell, the flavor, and everything is..., beauty, everything is coming? You daily see. So ordinarily you see heaps of dirt, but everything is there. Similarly, ordinarily we see this universe, but in every atom there is Kṛṣṇa. That was realized by Brahmā. Then he became the great personality to teach us. Tene brahma hṛdā ādi-kavaye, In this way he instructed ādi-kavi, the first learned man-kavi means learned man—Brahma, Vedic knowledge. So there was no other teacher. Kṛṣṇa taught him. Therefore we belong to the Brahma-sampradāya. Kṛṣṇa instructed Brahmā. Brahmā instructed Nārada. Nārada instructed Vyāsadeva. Vyāsadeva instructed Śukadeva. In this way our guru-paramparā system... Therefore we worship the guru as Vyāsa-pūjā because representative of Vyāsa. And who is Vyāsa? Representative of Nārada. What is Nārada? Representative of Brahmā. What is Brahmā? Representative of Kṛṣṇa. This is called paramparā system.